Background: Hypoglycemia has been reported as a complication of HBO therapy. A study of patient risk factors and the time course of glucose changes in patients undergoing treatment was used to develop a risk screening profile. A prospective analysis of the screening tool against glucose changes was studied to develop a comprehensive intervention and prevention program. Methods: A retrospective analysis of patients that had at least one HBO therapy rated hypoglycemic event reviewed histotical and risk data related to diabetes contror and complications. A risk screen score based on this was tested for sensitivity and specificity as a predictor of hypoglycemia as a potential complication of HBO therapy. Willing subjects (normal and diabetic) underwent glucose screening before, during. and after routine HBO therapy at 2.4 ATA. Results: A review of 19 patients revealed: 11 treated for diabetes > 20 yrs, 18 on insulin. with 8 on intensive therapy. 17 with previous hypoglycemic events. Glucose levels for nondiabetic subjects showed a small but significant decrease from pre to post treatment (p < 0.001). Glucose levels for diabetic patients showed an average drop of 60 mg/dl (p < 0.001). one hour post treatment glucose leveJs were unchanged from immediate post treatment (p < 0.15). An initial review of 28 patients that underwent risk screening generated scores from 4 to 16. higher scores correlating with increased risk. All patients with scores above 13 had glucose changes that put them at risk for hypoglycemia. There were 4 false positive screens. 0 false negatives: sensitivity of 100%, specificity of 86%. Conclusion: An analysis of patients suffering hypoglycemia as a result of HBO therapy was consistent with the diabetic literature. Intensive insulin therapy. antecedent hypoglycemia end lack of awareness of symptoms are all major risk factors. The time course profiles indicate that the time of lowest blood glucose occurs after HBO therapy and remains low (without intervention) for at least the first hour post treatment. An initial risk screening tool can be used to identify those patients that may require more aggressive intervention.